Chronic TBI patients should have a history of head trauma manifesting in one or more of the following:

1. Loss of consciousness
2. Post-traumatic amnesia
3. Focal neurologic deficits, seizure
4. Persistent symptoms of increased arousal (e.g. difficulty falling or staying asleep, anger and hypervigilance)
5. Impairment in social, occupational, or other important areas of functioning (e.g. problems with work and relationships.) Patients will be excluded from the study if we are unable to obtain informed consent and if they are non-communicative (i.e. in a vegetative state).

Chronic TBI Blast injury patients should have a history of head trauma manifesting in one or more of the following:

1. Loss of consciousness
2. Post-traumatic amnesia
3. Focal neurologic deficits, seizure
4. Persistent symptoms of increased arousal (e.g. difficulty falling or staying asleep, anger and hypervigilance)
5. Impairment in social, occupational, or other important areas of functioning (e.g. problems with work and relationships.) Patients will be excluded from the study if we are unable to obtain informed consent and if they are non-communicative (i.e. in a vegetative state).

Healthy volunteers include gender, age and race matched volunteers able to provide informed consent who have,

1. No significant medical history
2. Take no medications (other than birth control pills)
3. Fever free
4. No history of head trauma or recent injury/infection
5. No history of neurological or psychiatric disorders or alcohol or drug dependency.

one-time blood sample (~ 1 TBS) and saliva sample (~ 1 tsp)

The aim is to identify biomarkers in the blood of patients suffering from chronic TBI and to determine the similarities/differences between the blast and non-penetrating injury groups.

The aim is to identify biomarkers in the saliva of patients suffering from chronic TBI and to determine the similarities/differences between the blast and non-penetrating injury groups.